In recent years, there has been a series of products using bone conduction technology that becomes widely known as being installed in mobile phones. Various electronic apparatuses using the bone conduction technology, for example, application products such as a speaker or a hearing aid have been commercialized. Temuko Japan that holds a bone conduction related patent plans to launch products adopting the bone conduction technology, which include the speaker, a microphone, and the like which may be used even in a vacuum state and which are undeterred by a use place such as an underwater place, and the like.
In general, sound is recognized as the vibration of the air rings the eardrum, and the vibration is transferred to the cochlea. Contrary to this, in the bone conduction, the vibration is directly transferred from the bone to the cochlea. Because of this principle, the sound is heard even when the ears are closed. Therefore, when the cochlea and the auditory nerve are normal, even if there is a defect in the eardrum, the sound can be heard by the bone conduction.
The bone conduction technology itself has been established before, but there is a hinder in miniaturization for commercialization of the bone conduction technology as a product. This is because an output by the bone conduction is proportional to the size. As a result, Temuko Japan has invested heavily in developing bone conduction speakers in which the number of components is reduced and an internal structure is changed. In addition, the bone conduction speaker for voice communication adopting the bone conduction speaker is also under research.
In general, a sound or vibration output device is a device that outputs sound or vibration force, such as a speaker, a receiver, a buzzer, or a vibration motor (vibrator) that converts an electrical signal input from a signal source into a mechanical signal to output sound or generate the vibration force and also corresponds to a bone conduction output device.
The sound or vibration output device is applied to very various fields according to the size and the purpose. In particular, with the growth of the information and communication industry, adoption of a linear motion vibration motor rapidly increases, which excels a function of the existing rotary vibration motor, as a small sound or vibration output device widely used for vibration calling of a communication terminal, in particular, a small vibration motor, as a touch screen terminal including a smart phone drags popularity.
The reason why application of the linear motion vibration motor to a touch phone including the smart phone and a portable IT device such as a general cellular phone is extended is that a response speed is high and noise is small and a product life-span is also greatly improved as compared with the rotary vibration motor. The response speed means a time required to reach 50% of the vibration force at the maximum displacement and is the most important reason for adopting the linear motion vibration motor.
In recent years, the touch screen terminal evolves to the smart phone to download and use various applications and the applications carry out various functions and feedback vibration suitable for the functions is required and in order to meet the requirement, in the technical field, a vibration motor is required, which is higher in response speed, that is, reaction speed than the linear motion vibration motor in the related art.